What is it about?
Grid-connected power converters are widely used in applications like renewable energies, charging stations for electric vehicles and industrial electric drives. This paper proposes a novel hybrid converter topology for increasing the effciency and power density of the used power converters.
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Why is it important?
In order to meet harmonic limits, e.g. given by the grid code, conventional converter systems require passive LCL-filters composed of bulky inductors and capacitors, often entailing costs that surpass the costs of the power converter. Further disadvantages of passive LCL filters are substantial additional losses, a reduced dynamic performance, large volume and size as well as frequency dependency and oscillation susceptibility, requiring significant and lossy attenuation. In order to overcome the aforementioned disadvantages, this work focuses on the integration of new active filter topologies into grid-connected power converters and thereby eliminating the need for a passive LCL-filter.
Read the Original
This page is a summary of: Grid-connected medium voltage converters with parallel voltage-source active filters, IET Electric Power Applications, May 2019, the Institution of Engineering and Technology (the IET), DOI: 10.1049/iet-epa.2019.0021.
You can read the full text:
Grid-connected Voltage Source Converters with integrated Multilevel-Based Active Filters
Low- and medium voltage power converters for grid applications require bulky and expensive LCL-filters in order to meet the harmonic limits defined by the grid code. This paper presents a novel hybrid converter topology with smaller passive components, composed of a high power main converter with an integrated low power active filter. The presented coupled control strategies for a current-source and a voltage-source topology enable the immediate mitigation of the switching frequency current ripple, significantly decreasing the total harmonic distortion (THD) of the output current to below 0.5% and thereby eliminating the need for a passive LCL-filter. Compared to LCL-filter based converter systems, a reduction of the inductive component expenditure of up to 50% is achievable even for a very low active filter to main converter power rating ratio of 10%. The outstanding harmonic performance and reduced passive component demand of the hybrid converter allow increased power density and efficiency as well as lower costs of low- and medium voltage power converters.
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